Why does enter submit a form differently than clicking submit in IE 7?

In IE 7 the zip code search form on my page reacts differently when someone clicks submit vs pressing enter. It works correctly when sumbmit is clicked and incorrectly when enter is pressed.

http://getridofit.com

<form name="zip" action="<?php bloginfo('url'); ?>" metho开发者_开发技巧d="get">
<input type="text" id="zipper" name="locations" size="5" maxlength="5" class="junk-input" onsubmit="return checkForm()" />
<input type="submit" value="" name="schedule" src="/wp-content/uploads/remove-my-junk.png"  align="center" class="junk-button" style="background: #f67a3e url(/wp-content/uploads/remove-my-junk.png); border: none; width: 201px; height: 45px;"/>
</form>

The correct result for a zip search of 85718 looks like this: http://getridofit.com/l/85718/?schedule but pressing enter produces a result like this: http://getridofit.com/l/85718/

Because the button wasnt clicked in order to submit the form. If you dont click the button then the input for @name[schedule] isnt sent. However if that button input has focus when enter is pressed i think it will send it along properly... You might jsut want to make schedule a hidden input.

It looks like you are checking for the presence of the submit button variable (schedule) in the URL bar. The submit button variable is only supposed to be submitted when the user physically clicks the the submit button. However, I can't reproduce the problem in Safari, so it may also depend on what your JavaScript is doing when the form is submitted.